The proposed research will be a comprehensive study of the effects of anesthesia on cardiovascular reflexes. This area of investigation has been well studied, yet major disagreements as to anesthetic action on central vasomotor centers, synaptic transmission and cardiac and peripheral vascular responsiveness still exist. By employing techniques developed to study all levels of cardiovascular reflexes, from receptor to effector organs, this study will examine the effects of various anesthetics on cardiovascular reflex regulation in the dog. Various anesthetics which have been reported to either increase or decrease reflex activity through preferential activation or depression of central vasomotor centers will be examined to determine the extent of their different actions. Reflex alteration due to anesthesia will be examined by comparing reflex responses in conscious and anesthetized animals. The site of anesthetic action will be determined by examining the effect of type and dosage of anesthetics on baroreceptor and cardiopulmonary receptor afferent activity, central integratory action, sympathetic efferent activity, and effector organ response of the heart and selected vascular beds. A specific neuroanatomical technique employing 14C-2-deoxyglucose will be used to map the extent and sites of reflex activation of central vasomotor centers with each anesthetic used. Finally, anesthetic effect on ganglionic transmission will be critically examined using intracellular recording techniques on stellate ganglion cells. The proposed research will therefore provide new and detailed information on the effect of anesthetics in reflex regulation of the cardiovascular system. Precise information regarding the site/sites of reflex alteration due to various types and dosages of anesthesia will be obtained. By careful examination of anesthetics with seemingly different mechanisms, clinically relevant information will be obtained regarding anesthetic actions on cardiovascular regulation, which may provide insight into anesthetic choice under different clinical situations.